JP2011134916A - Material gas concentration control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material gas concentration control system capable of preventing the occurrence of a state such that when a concentration of a material gas is held in a constant state by a certain set concentration, partial pressure of the material gas becomes extremely low, thereby, total pressure corresponding to the partial pressure of the material gas cannot be achieved within a movable range of a valve, and the concentration of the material gas cannot be held constant at the set concentration. <P>SOLUTION: The material gas concentration control system is used for a material vaporization system 100, and includes: a first valve 23 provided on a lead-out pipe 12; a concentration measuring unit CS which measures the concentration of the material gas in a mixed gas; a concentration control unit CC which controls the degree of opening of the first valve 23 so that the measured concentration of the material gas measured by the concentration measuring unit CS reaches the predetermined set concentration; a temperature controller 41 which controls the temperature in a tank so as to be the set temperature; and a temperature setting unit 42 which sets the set temperature of the temperature controller. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a system for controlling a concentration of a vaporized material gas in a material vaporization system that introduces a carrier gas into a solid or liquid material accommodated in a tank and vaporizes the material.

  The present applicant has applied for a concentration control system for use in this type of material vaporization system to keep the concentration of the material gas constant. The concentration control system includes a first valve, a partial pressure measuring sensor for measuring a partial pressure of the material gas, a pressure of the mixed gas, a lead-out pipe through which a mixed gas of the carrier gas and the material gas is led out from the tank. A total pressure measuring sensor that measures the total pressure, and a concentration measuring unit that measures the concentration of the material gas in the mixed gas by dividing the measured partial pressure by the total pressure, and the concentration measuring unit And a concentration control unit for controlling the opening degree of the first valve so that the measured concentration becomes a predetermined set concentration.

  According to the concentration control system configured as described above, even if the material in the tank is not vaporized at the saturated vapor pressure and the vaporization state fluctuates and the partial pressure of the material gas fluctuates, the fluctuation Accordingly, the total pressure of the mixed gas is controlled by the first valve. Therefore, the concentration of the material gas can be kept constant at the set concentration regardless of the generation state of the material gas in the tank.

Japanese Patent Application No. 2008-282622

  By the way, if concentration control is continued, the partial pressure of the material gas which vaporizes the material in a tank by the amount of material decreasing will fall. If the material is a solid, the surface area is reduced, and the area in contact with the carrier gas is reduced. If the material is a liquid, the liquid level is lowered, and the bubble of the carrier gas is reduced. This is due to a decrease in the amount of material gas generated due to a decrease in the contactable time and a decrease in temperature in the tank due to the heat of vaporization taken away during evaporation.

  When the generation amount of the material gas is reduced and the partial pressure of the material gas is reduced, the concentration control system described above sets the first valve to reduce the total pressure in order to keep the concentration of the material gas constant. Control. In this case, in order to reduce the total pressure, the opening degree of the first valve is controlled to be larger.

  However, since the first valve has a movable range, if the first valve is fully opened, the total pressure of the mixed gas cannot be further reduced. Therefore, if the partial pressure of the material gas becomes too small, the total pressure cannot be reduced following the pressure, and the concentration of the material gas cannot be maintained at the set concentration.

  In addition, not only when the concentration is kept constant, but also when the flow rate of the material gas is kept constant by controlling the flow rate of the carrier gas, the flow rate of the carrier gas is similarly caused by a decrease in the generated amount of the material gas. The opening degree of the control valve becomes the opening limit opening degree, and the flow control of the material gas may become impossible.

  The present invention has been made in view of the above-described problems. For example, when the concentration of the material gas is kept constant at a certain set concentration, the partial pressure of the material gas becomes very low, and the valve can be moved. The material gas concentration control system that prevents the situation in which the total pressure corresponding to the partial pressure of the material gas cannot be achieved within the range and the concentration of the material gas cannot be kept constant at the set concentration. The purpose is to provide. It is another object of the present invention to provide a material gas flow rate control system that can prevent a situation in which the amount of material gas generated is reduced and the material gas flow rate cannot be kept constant.

  That is, the material gas concentration control system of the present invention includes a tank that contains a material, an introduction pipe that introduces a carrier gas that vaporizes the contained material into the tank, a material gas that vaporizes the material, and the carrier gas. Used in a material vaporization system including a lead-out pipe for leading out the mixed gas from the tank, and a first valve provided on the lead-out pipe, and the concentration of the material gas in the mixed gas is measured A concentration measuring unit, a concentration control unit for controlling the opening of the first valve so that the measured concentration of the material gas measured by the concentration measuring unit becomes a predetermined set concentration, A temperature controller for adjusting the temperature so as to be a set temperature; and a temperature setting unit for setting the set temperature of the temperature adjuster, wherein the opening degree of the first valve is an open limit opening of a movable range. In the case of exceeding the open side threshold opening determined based, the temperature setting unit, and changes the set temperature to a temperature higher than the set temperature that is set at that time.

  The program used for the material gas concentration control system of the present invention includes a first valve provided on the outlet pipe, a concentration measuring unit for measuring the concentration of the material gas in the mixed gas, and a predetermined setting. Used in a material gas concentration control system including a concentration control unit that controls the opening degree of the first valve so as to achieve a concentration, and a temperature controller that adjusts the temperature in the tank to a set temperature. A temperature setting unit that sets a set temperature of the temperature controller, wherein the measured concentration of the material gas measured by the concentration measuring unit includes an opening of the first valve in a movable range. When the opening side threshold opening determined based on the opening limit opening is exceeded, the temperature setting unit changes the set temperature to a temperature higher than the set temperature set at that time. To do.

  In such a case, when the concentration of the material gas is reduced while the concentration control is continued so that the concentration of the material gas becomes the set concentration, the partial pressure of the material gas is reduced. Even if the opening degree of the first valve approaches the opening limit opening degree while the total pressure is continuously lowered to keep the concentration at the set concentration, the temperature setting unit at that time, Is set to be higher than the temperature at the time when the opening side threshold opening is reached, and the material gas generation amount is increased by increasing the saturated vapor pressure of the material gas, thereby increasing the partial pressure of the material gas. it can. Therefore, in order to make the concentration constant when the partial pressure of the material gas increases, it is necessary to increase the total pressure. Therefore, the valve opening is closer to the closing side than the opening at the time when the open side threshold opening is exceeded. The opening is controlled. That is, when the partial pressure of the material gas falls below a certain limit value, the temperature setting unit changes the set temperature to a higher temperature to increase the partial pressure of the material gas, so that the first valve is opened. The concentration control is not performed near the opening limit opening degree, but the concentration control can be performed with a sufficient margin at the center of the movable range.

  As described above, due to a decrease in the partial pressure of the material gas, it is necessary to control the concentration in a region beyond the movable range of the first valve, and the first valve stops at the opening limit opening. It is possible to prevent the density control from becoming impossible.

  Furthermore, according to the material gas concentration control system having such a configuration, it is possible to realize concentration control capable of allowing fluctuations in the partial pressure of the material gas by controlling the total pressure using the first valve. Therefore, it is not necessary to strictly control the amount of material gas generated by temperature control. Therefore, in order to control the concentration, it is only necessary to use a temperature controller and a temperature setting unit that can only deal with a special situation that exceeds the movable range of the first valve. May be. Therefore, since it is not necessary to use a high-performance one, even if a simple and inexpensive temperature controller and temperature setting unit are used, the concentration control cannot be performed by exceeding the movable range of the first valve as described above. Can be prevented.

  When temperature control is started after detecting that the opening of the first valve has reached or is close to the open side threshold opening, depending on the delay in temperature control, the partial pressure of the material gas Inertia acts in the decreasing direction, and the first valve may reach the opening limit opening. In order to prevent such a problem, what is necessary is just to change the said threshold value according to the change rate of the opening degree of the said 1st valve | bulb. If this is the case, when the rate of change is large, allow for a margin so that the difference between the opening threshold opening and the opening limit opening is large, and when the rate of change is small, the difference in opening is large. If the value is set to be small, for example, it is possible to perform safe concentration control that makes it easier to avoid a state where control is impossible.

  The partial pressure of the material gas is monitored, and if the partial pressure has decreased, the partial pressure may be increased to some extent so that the concentration control can be performed within the movable range of the opening of the first valve. . Specifically, a tank for storing the material, an introduction pipe for introducing a carrier gas for vaporizing the stored material into the tank, and a mixed gas of the material gas evaporated from the material and the carrier gas from the tank. A material vaporization system comprising a lead-out pipe for leading out, wherein the first valve provided on the lead-out pipe, a partial pressure measuring sensor for measuring the partial pressure of the material gas, and the mixed gas A total pressure measuring sensor for measuring a total pressure, a concentration measuring unit for measuring a concentration of the material gas in the mixed gas based on the partial pressure and the total pressure, and the concentration measuring unit measured by the concentration measuring unit A concentration control unit for controlling the opening degree of the first valve so that the measured concentration of the material gas becomes a predetermined set concentration, and a temperature controller for adjusting the temperature in the tank to the set temperature. The above A temperature setting unit for setting a set temperature in the controller, and a partial pressure measured by the partial pressure measuring sensor is a lower limit threshold partial pressure determined based on an opening limit opening of a movable range of the first valve. When the temperature is lower, the temperature setting unit may change the set temperature to a temperature higher than the set temperature set at that time.

  In order to prevent the concentration control from becoming impossible due to the opening degree of the first valve being the opening limit opening degree, use a method other than the method of adjusting the partial pressure of the material gas using the temperature control. It doesn't matter. Specifically, a tank for storing the material, an introduction pipe for introducing a carrier gas for vaporizing the stored material into the tank, and a mixed gas of the material gas evaporated from the material and the carrier gas from the tank. What is used in a material vaporization system including a lead-out pipe for leading out, is a first valve provided on the lead-out pipe, a concentration measuring unit that measures the concentration of the material gas in the mixed gas, and the concentration A concentration control unit for controlling the opening degree of the first valve so that the measured concentration of the material gas measured by the measuring unit becomes a predetermined set concentration; and provided upstream or downstream of the first valve. An auxiliary valve and an auxiliary valve control unit for controlling the opening degree of the auxiliary valve, wherein the opening degree of the first valve is determined based on the opening limit opening degree of the movable range. The auxiliary valve control unit changes the opening of the auxiliary valve to an opening on the open side with respect to the opening set at that time. Any system can be used. If this is the case, when the first valve approaches the opening limit opening, the opening of the auxiliary valve is opened to further reduce the total pressure in an auxiliary manner. Corresponding to the decrease in partial pressure, the concentration can be kept constant at the set concentration.

  The partial pressure of the material gas is increased in the same way as preventing the situation where the set concentration cannot be reached even if the first valve reaches the opening limit opening degree due to the excessive reduction of the partial pressure of the material gas. By excessively increasing the total pressure in accordance therewith, it may be possible to avoid a problem that the set concentration cannot be achieved even when the first valve reaches the closing limit opening. Specifically, a tank for storing a material, an introduction pipe for introducing a carrier gas for vaporizing the stored material into the tank, and a mixed gas of the material gas vaporized from the material and the carrier gas from the tank. What is used in a material vaporization system including a lead-out pipe for leading out, is a first valve provided on the lead-out pipe, a concentration measuring unit that measures the concentration of the material gas in the mixed gas, and the concentration A concentration control unit for controlling the opening degree of the first valve so that the measured concentration of the material gas measured by the measuring unit becomes a predetermined set concentration, and the temperature in the tank becomes the set temperature. And a temperature setting unit that sets a set temperature in the temperature controller, and the opening degree of the first valve is determined based on the closing limit opening degree of the movable range. If it falls below the degree, the temperature setting unit may be a material gas concentration control system and changes the set temperature to a lower temperature than the set temperature that is set at that time.

  Even when it is desired to keep the flow rate of the material gas, rather than the concentration of the material gas in the mixed gas, the flow rate control valve is reduced due to a decrease in the amount of material gas generated due to a decrease in the material. Even if the opening limit is reached, the set flow rate may not be achieved. In order to prevent such a problem, a tank for containing the material, an introduction pipe for introducing a carrier gas for vaporizing the contained material into the tank, a mixed gas of the material gas vaporized from the material and the carrier gas A second valve provided on the introduction pipe, wherein the second valve is provided on the introduction pipe.

  A material gas flow rate measurement unit for measuring the flow rate of the material gas, and an opening degree of the first valve so that the measured flow rate of the material gas measured by the material gas flow rate measurement unit becomes a predetermined set flow rate. A material gas flow rate control unit for controlling the temperature, a temperature controller for adjusting the temperature in the tank to a set temperature, and a temperature setting unit for setting the set temperature of the temperature controller, the second When the opening degree of the valve exceeds the opening side threshold opening degree determined based on the opening limit opening degree of the movable range, the temperature setting unit is set to a temperature higher than the set temperature set at that time. Any material gas flow rate control system characterized by changing the set temperature may be used. In such a case, when the second valve approaches the opening limit opening, the temperature in the tank is increased to increase the amount of the material gas generated, and the opening of the second valve is movable. Since control can be performed at the center of the range, a situation in which the flow rate of the material gas becomes uncontrollable can be avoided, and the material gas can always flow at a constant flow rate.

  As described above, according to the material gas concentration control system of the present invention, when the partial pressure of the material gas is reduced during the concentration control, the opening of the first valve approaches the open limit opening, and the concentration is further increased. Before the control cannot be continued, the temperature setting unit increases the set temperature to increase the partial pressure of the material gas to some extent, so that the total pressure to be achieved also increases, Concentration control can be reliably performed within the movable range, and it is possible to prevent a problem that concentration control becomes impossible when the first valve is at the opening limit opening degree and cannot be moved any more.

1 is a schematic structure of a material gas concentration control system according to an embodiment of the present invention. The functional block diagram of the material gas concentration control system in the embodiment. The flowchart which shows the operation | movement of the concentration control of the material gas concentration control system in the embodiment. The flowchart which shows the operation | movement of the flow control of the material gas concentration control system in the embodiment. The graph which shows that concentration control can be performed within the movable range of a 1st valve | bulb by the setting temperature change of the material gas concentration control system in the embodiment. The typical structure of the material gas concentration control system which concerns on another embodiment of this invention. The typical structure of the material gas concentration control system which concerns on another embodiment of this invention. The typical structure of the material gas concentration control system which concerns on different embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  The material gas concentration control system 100 of the present embodiment is used, for example, to supply TMIn (trimethylindium) at a constant concentration to an MOCVD film forming apparatus which is a kind of semiconductor manufacturing apparatus. More specifically, it is used in a bubbling system 1 that vaporizes a solid material of TMIn and supplies it to a chamber that is a film forming chamber. TMIn corresponds to the material in the claims, and the bubbling system 1 corresponds to the material vaporization system in the claims. Here, even if the material is a liquid material, the present invention can achieve the same effect. Further, the material concentration control system of the present invention is not limited to the concentration control of the material gas vaporized from the TMIn solid material. For example, it can also be used to stably supply an IPA (isopropyl alcohol) concentration in a drying treatment tank of a CVD film forming apparatus or the like or a wafer cleaning apparatus used in a semiconductor manufacturing process. In addition, the present invention is not limited to manufacturing processes for semiconductors, FPDs, optical devices, MEMS, and the like, and can be used for gas supply apparatuses using the bubbling system 1.

  As shown in FIG. 1, the bubbling system 1 includes a tank 13 for storing material L, an introduction pipe 11 for introducing a carrier gas into the material L stored in the tank 13 and bubbling, and a tank 13. A lead-out pipe 12 for deriving a mixed gas of the material gas vaporized from the material L and the carrier gas from the upper space N of the stored material L is provided. A temperature sensor T for measuring the temperature in the tank 13 is attached to the tank 13.

  The material gas concentration control system 100 is provided in the introduction pipe 11, and is provided in the mass flow controller 3 (flow rate controller) for controlling the flow rate of the carrier gas and the outlet pipe 12, and the material in the mixed gas. It is comprised from the concrete controller 2 (concentration controller) for performing density | concentration control of gas. The concrete controller 2 of the present embodiment performs concentration control by controlling the total pressure of the mixed gas. Further, in addition to such a configuration, the material gas concentration control system 100 further includes a temperature control mechanism for keeping the temperature in the tank 13 constant.

  In the following, with reference to FIGS. 1 and 2, each device will be described in detail for each unit in the order of the conch controller 2, the mass flow controller 3, and the temperature control mechanism.

  <Conc controller configuration>

  The concrete controller 2 includes a concentration measuring unit CS that measures the concentration of the material gas in the mixed gas, and a pressure gauge 22 that is a pressure measuring unit that measures the pressure (total pressure) of the mixed gas, which is the pressure in the tank 13. And a first valve 23 for controlling the total pressure of the mixed gas according to the opening of the valve body is provided in this order from the upstream side, and further includes a concrete controller control unit 24. Here, in order to control the concentration of the material gas in the mixed gas, the pressure gauge 22 needs to be provided upstream of the first valve 23. This is because the total pressure in the tank 13 is accurately measured, the concentration of the material gas in the mixed gas is accurately calculated, and the change in the vaporized state of the material L can be matched.

  The concentration measuring unit CS includes a partial pressure measuring sensor 21 that measures a partial pressure of a material gas by a non-dispersive infrared absorption method, a partial pressure of the material gas measured by the partial pressure measuring sensor 21, and the pressure gauge 22. And a concentration calculation unit 241 that calculates the concentration of the material gas in the mixed gas based on the total pressure that is the measurement pressure measured by the above. Here, the concentration of the material gas in the mixed gas is calculated by dividing the partial pressure of the material gas by the total pressure of the mixed gas. Such a concentration calculation method is derived on the basis of a gas equation of state.

  The concrete controller control unit 24 includes the above-described density calculation unit 241 and the density control unit CC. The concentration control unit CC controls the first valve 23 so that the measured concentration measured by the concentration measuring unit CS results in a predetermined set concentration. The first valve control unit 242 and the first control unit This is composed of a set pressure setting unit 243 for setting a set pressure in the one-valve control unit 242.

  The first valve control unit 242 controls the opening degree of the first valve 23 so that the pressure (total pressure) measured by the pressure gauge 22 becomes a set pressure that is set by the set pressure setting unit 243. To do.

  The set pressure setting unit 243 sets the set pressure as a temporary set pressure that is a tank internal pressure calculated by a total pressure calculation unit 244 described later in a certain period after the set concentration is changed, and in other periods. Is to change the predetermined set pressure so that the deviation between the measured concentration measured by the concentration measuring unit CS and the set concentration becomes smaller.

  Specifically, when the measured concentration is higher than the set concentration, the concentration is expressed by partial pressure / total pressure, and therefore the concentration can be lowered by increasing the total pressure. Accordingly, when the measured concentration is higher than the set concentration, the set pressure setting unit 243 changes the set pressure to increase the total pressure with respect to the first valve control unit 242. As a result, the first valve control unit 242 performs control to reduce the opening degree of the first valve 23. If the measured concentration is lower than the set concentration, the reverse is performed.

  In this way, changing the set pressure in such a direction that the deviation between the measured concentration and the set concentration becomes smaller means that if the measured concentration is higher than the set concentration, the set pressure is changed higher and the measured concentration is higher than the set concentration. If it is lower, it means changing the set pressure lower.

  The controller controller 24 uses a computer and includes an internal bus, a CPU, a memory, an I / O channel, an A / D converter, a D / A converter, and the like. Then, the CPU and peripheral devices operate according to a predetermined program stored in advance in the memory, so that the functions as the first valve control unit 242, the concentration calculation unit 241, and the set pressure setting unit 243 are exhibited. It is. Here, only the first valve control unit 242 is configured by an independent control circuit such as a one-chip microcomputer so as to receive a set pressure, and the pressure gauge 22 and the first valve 23 are set as one unit. It is configured so that pressure control can be easily performed simply by inputting. With such a configuration of the control unit, it is possible to use a control circuit or software that has been developed for pressure control in the past for concentration control, and thus it is possible to prevent an increase in design and development costs.

  Thus, the concrete controller 2 performs the concentration control of the mixed gas as a single unit.

  <Configuration of mass flow controller>

  Next, each part of the mass flow controller 3 will be described. The mass flow controller 3 includes a thermal flow meter 31 that is a flow rate measuring unit that measures the mass flow rate of the carrier gas flowing into the introduction pipe 11, and a second valve 32 that adjusts the flow rate of the carrier gas according to the opening of the valve body. Are provided from the upstream in this order, and further, a mass flow controller control unit 33 is provided. As the flow rate measuring unit, a differential pressure type may be used.

  The mass flow controller control unit 33 is based on a carrier gas flow rate calculation unit 331 that calculates the flow rate of a carrier gas based on a signal from the thermal type flow meter 31, and based on the measured concentration of the material gas and the measured flow rate of the carrier gas. And a flow rate control unit FC that calculates the flow rate of the material gas or mixed gas flowing through the outlet pipe 12 and controls the opening degree of the second valve 32 so that the calculated flow rate becomes a predetermined set flow rate. It is.

  The flow rate control unit FC includes a second valve control unit 332 and a set carrier gas flow rate setting unit 333 that sets a set flow rate in the second valve control unit 332.

  The second valve control unit 332 controls the opening degree of the second valve 32 so that the measured carrier gas flow rate becomes the set carrier gas flow rate set by the set carrier gas flow rate setting unit 333. .

  The set carrier gas flow rate setting unit 333 changes the preset set carrier gas flow rate in a direction in which the deviation between the calculated flow rate and the set set flow rate becomes smaller. More specifically, reducing the deviation between the calculated flow rate and the set flow rate that has been set, when the calculated flow rate of the material gas or mixed gas is greater than the set flow rate of the material gas or mixed gas, the concentration Assuming that the concentration is kept constant by the control unit CC, the set carrier gas flow rate is changed for the second valve control unit 332 so as to reduce the flow rate of the inflowing carrier gas. If the calculated flow rate is smaller than the set flow rate, the reverse is performed. Since the concentration is expressed by partial pressure / total pressure, it can also be expressed as (mass flow rate of material gas) / (total mass flow rate = mass flow rate of material gas + mass flow rate of carrier gas). This is because, if maintained, the increase and decrease in the mass flow rate of the carrier gas can directly increase and decrease the mass flow rate and the total flow rate of the material gas. Note that when the calculated flow rate is smaller than the set flow rate, an operation opposite to that when the calculated flow rate is large is performed.

  The carrier gas flow rate calculation unit 331 and the second valve control unit 332 function by a control circuit BF including a CPU, a memory, an I / O channel, an A / D converter, a D / A converter, and the like. This control circuit BF is specialized for flow rate control, and is configured to receive a flow rate setting value signal that is a flow rate value to be controlled by the mass flow controller 3 and a signal from the thermal type flow meter 31. It is what. The set carrier gas flow rate setting unit 333 is realized by a general-purpose one-chip microcomputer or the like.

  As described above, the mass flow controller 3 performs only the flow control of the carrier gas in the introduction pipe 11, and as a result, performs the flow control of the material gas or the mixed gas.

  <Operation of concrete controller and mass flow controller>

  Next, the control operation of the material gas concentration in the mixed gas and the control operation of the flow rate of the mixed gas and the material gas will be described with reference to the flowcharts of FIGS.

  First, the operation when the concentration control is performed by controlling the opening degree of the first valve 23 so that the set concentration is set will be described with reference to FIG.

  Based on the partial pressure of the material gas measured by the partial pressure measurement sensor 21 and the total pressure of the mixed gas measured by the pressure gauge 22, the concentration calculation unit 241 calculates the concentration of the material gas in the mixed gas using the equation (1). ).

  C = Pz / Pt (1)

  Here, C is the concentration, Pz is the partial pressure of the material gas, and Pt is the total pressure of the mixed gas.

  During normal operation, if the concentration measured by the concentration measuring unit is different from the set concentration set in the set pressure setting unit 243, the partial pressure of the material gas measured by the partial pressure measuring sensor 21 Based on Pz and the set concentration C0, the set pressure setting unit 243 changes the set pressure Pt0 as follows (step S1) according to the equation (2).

  Pt0 = Pz / C0 (2)

  Here, Pz is a value that is constantly measured by the partial pressure measuring sensor 21, and C0 is known because it is a set concentration.

  When the set pressure is changed to Pt0, the first valve control unit 242 opens the first valve 23 so that the deviation between the pressure (total pressure) Pt measured by the pressure gauge 22 and the set pressure Pt0 becomes small. Is controlled (step S2).

  If the partial pressure Pz of the material gas does not change while the measurement pressure Pt is made to follow the set pressure Pt0, the concentration of the material gas in the mixed gas that is finally measured becomes the set concentration C0.

  When the partial pressure Pz of the material gas changes during the follow-up, the set pressure setting unit 243 changes the set pressure Pt0 again according to the equation (2) so that the set concentration C0 is obtained.

  Next, the flow control of the material gas or the total flow rate in the outlet pipe 12 will be described with reference to FIG. Note that the mass flow controller 3 controls the flow rate of the carrier gas regardless of the concentration control of the conc controller 2 described above.

  It is assumed that the material gas set flow rate Qz0 is set in the set carrier gas flow rate setting unit 333. First, there is a relationship such as the following formula (3) between the flow rate and the concentration.

  C = Pz / Pt = Qz / Qt = Qz / (Qc + Qz) (3)

  Here, Qz is the mass flow rate of the material, Qt is the mass flow rate of the mixed gas, and Qc is the mass flow rate of the carrier gas.

  The set carrier gas flow rate setting unit 333 sets the set carrier gas flow rate Qc0 by the following formula (4) obtained by modifying the formula (3) (step ST1).

  Qc0 = Qz0 (1-C) / C (4)

  Here, the density C is a value that is always measured by the density measuring unit CS, and Qz0 is also a set value and is known.

  When the set carrier gas flow rate is changed to Qc0, the second valve control unit 332 causes the second valve 32 to reduce the deviation between the carrier gas flow rate Qc measured by the flow rate measuring unit and the set carrier gas flow rate Qc0. Is controlled (step ST2).

  If the concentration C does not change while the measured carrier gas flow rate Qc is made to follow the set carrier gas flow rate Qc0, the measured carrier gas flow rate finally measured becomes the set carrier gas flow rate Qc0.

  If the concentration C fluctuates during the follow-up, the set carrier gas flow rate setting unit 333 resets the set carrier gas flow rate Qc0 again by Equation (4) so that the predetermined material gas flow rate Qz0 is obtained.

  In this way, the concent controller 2 and the mass flow controller 3 cooperate to perform concentration control using the total pressure that can be easily controlled by the first valve 23 as a control variable. However, even if the vaporization does not sufficiently evaporate to the saturated vapor pressure or the vaporization fluctuates, the concentration of the material gas in the mixed gas can be kept constant at the set concentration.

  <Configuration of temperature control mechanism>

  Next, the configuration and operation of the temperature control mechanism 4 will be described. The temperature adjustment mechanism 4 includes a temperature adjuster 41 that adjusts the temperature so as to be the set temperature of the bubbling system 1, and a temperature setting unit 42 that sets the set temperature of the temperature adjuster 41.

  The temperature controller 41 is a heater that acquires the temperature in the tank from the temperature sensor T and performs on / off control so that the measured temperature becomes a set temperature. The temperature controller 41 and the tank are surrounded by a heat insulating tank. The temperature controller 41 may be one that keeps the temperature in the tank constant by PID control.

  When the opening degree of the first valve 23 exceeds the opening side threshold opening degree determined based on the opening limit opening degree of the movable range, the temperature setting unit 42 is set temperature set at that time. The set temperature is changed to a higher temperature.

  More specifically, the temperature setting unit 42 has its function realized by a computer or the like, acquires the opening degree of the first valve 23, and the measured opening degree is the opening side threshold value. When the measured opening degree exceeds the open-side threshold opening degree in the opening degree comparing part 421 for comparing whether or not the opening degree is exceeded and the opening degree comparing part 421, the set temperature is It comprises a temperature changing unit 422 that changes to a higher temperature.

  The opening degree comparison unit 421 is configured to change the opening side threshold opening degree to be set based on the characteristics of the material and the rate of change of the opening degree over time. Specifically, the opening degree comparing unit 421 correlates to the absolute value of the difference between the opening limit opening degree and the opening side threshold opening degree as the rate of change of the opening degree of the first valve 23 increases. The opening-side threshold opening is set so as to increase. When the opening degree of the first valve 23 exceeds the open-side threshold opening degree, a signal to that effect is transmitted to the temperature changing unit 422.

  The temperature changing unit 422 changes the temperature of the first valve 23 to a set temperature higher than the currently set temperature when the opening of the first valve 23 exceeds the open side threshold value. In the case of the present embodiment, setting the set temperature to a temperature higher than the current temperature is set to increase by a predetermined temperature. For example, the set temperature is increased so that the concentration control is performed in the vicinity of the substantially median value in the movable range of the opening degree of the first valve 23.

  In the material gas concentration control system 100 configured as described above, the operation of the temperature control mechanism 4 when the partial pressure of the material gas generated from the tank 3 is reduced will be described.

  When the concentration of the material gas is kept constant at the set concentration by the concrete controller 2, the amount of gas vaporized from the material decreases due to a decrease in the amount of material and the like as time elapses. When the generation amount of the material gas decreases, the partial pressure of the material gas in the tank 13 decreases. In order to keep the concentration constant, the concrete controller 2 controls the opening of the first valve 23 to increase toward the open side so as to reduce the total pressure of the mixed gas in accordance with the decrease in the partial pressure of the material gas. To do.

  The opening degree comparison unit 421 is configured such that the concentration of the material gas is kept constant at a set concentration, and the first valve 23 is in a state where the opening degree of the first valve 23 has not reached the open side threshold opening degree. The change rate of the opening is monitored, and the open-side threshold opening is changed based on the change rate at every sampling period or every fixed period. Then, when the opening degree comparing unit 421 compares the opening degree of the first valve 23 with the opening side threshold opening degree and determines that the opening side threshold opening degree is exceeded, the opening degree comparing unit 421 transmits the fact to the temperature changing unit 422. .

  The temperature changing unit 422 increases the set temperature by a predetermined value from the currently set temperature to a new set temperature.

  The reason why the first valve 23 can always perform concentration control within the movable range by changing the set temperature in this way will be described with reference to FIG. FIG. 5 shows the set concentration on the horizontal axis, the total pressure of the mixed gas on the vertical axis, the total pressure at the opening limit opening of the first valve 23 with a broken line, and the closing limit opening of the first valve 23 with a dashed line. The total pressure is shown, and the range of the total pressure that can be achieved in the movable range of the first valve 23 by the region sandwiched between the broken line and the alternate long and short dash line is shown. A curve drawn by a solid line is a curve in the case where the partial pressure Pz of the material gas is constant at a certain temperature, and is drawn based on the formula Pt = Pz / C. The curve drawn on the lower side is when the temperature of the material gas is 15 ° C., and the curve drawn on the upper side is when the temperature of the material gas is 25 ° C.

  As shown in FIG. 5, if the set concentration is 0.25%, the open limit opening is exceeded in the case of a curve at 15 ° C., so that the total pressure cannot be achieved by the first valve 23 and concentration control is impossible. Become. However, if the set temperature is changed to 25 ° C. at the open-side threshold opening shown in FIG. 5, when the set concentration is 0.25%, all the achievable within the movable range as shown in FIG. Since it is a pressure, it can be controlled to a set concentration.

  As described above, according to the material gas concentration control system 100 of the present embodiment, even if the partial pressure of the material gas decreases while the control is continued so as to keep the concentration and flow rate of the material gas constant, When the opening degree of the first valve 23 exceeds the open-side threshold opening degree, the temperature adjustment mechanism 4 changes the set temperature to a higher temperature to increase the partial pressure of the material gas and It is possible to perform density control within the movable range. Accordingly, it is possible to prevent the problem that the concentration control becomes impossible by reaching the opening limit opening degree, and it is possible to always keep the material gas concentration constant.

  Moreover, although it is difficult to always control the temperature in the tank 13 that changes depending on various factors such as the generation state of the material gas and the remaining amount thereof in a very short time, the temperature control mechanism 4 of the present embodiment is When the opening degree of the first valve 23 exceeds the open side threshold opening degree, the set temperature is changed to roughly increase the temperature in the tank, so only a very simple temperature control is performed. It is easy to achieve the desired control. That is, even if it is an inexpensive temperature control device, it is possible to prevent the control command that is sufficiently beyond the movable range of the first control valve 23, which is the object of the present embodiment, from being stopped.

  Other embodiments will be described. In the following description, the same reference numerals are given to members corresponding to the above-described embodiment.

  In the above embodiment, the concentration of the material gas in the mixed gas is controlled by controlling the first valve 23 so that the total pressure of the mixed gas becomes the set pressure. However, the concentration measured by the concentration measuring unit CS As a control variable, the first valve 23 may be controlled so as to obtain a set concentration.

  In the above-described embodiment, not only the concentration of the material gas but also the outflow rate thereof is controlled together. However, if only the concentration needs to be controlled, the mass controller 3 is not provided and only the conch controller 2 is provided. The control may be performed according to the above. That is, a tank for storing the material, an introduction pipe for introducing a carrier gas for vaporizing the contained material into the tank, and a lead-out pipe for deriving a mixed gas of the material gas vaporized from the material and the carrier gas from the tank The first valve provided on the outlet pipe, the concentration measuring unit for measuring the concentration of the material gas in the mixed gas, and the concentration measuring unit. A material gas concentration control system comprising a concentration control unit for controlling the opening degree of the first valve so that the measured concentration of the material gas becomes a predetermined set concentration. I do not care.

  Even in such a case, the concentration measuring unit itself measures the concentration of the material gas in the mixed gas, and the concentration control unit controls the opening degree of the first valve so as to be a preset concentration. Even if the amount of material gas generated changes when the material is not vaporized with saturated vapor pressure in the tank or when the bubbling state changes, the concentration can be kept constant regardless of the change. it can.

  The concentration measuring unit CS calculates the concentration based on the partial pressure and the total pressure. However, the concentration measuring unit CS may directly measure the concentration. Further, the partial pressure measurement sensor 21 is not limited to the non-dispersive infrared absorption method, and may be an FTIR spectroscopy method, a laser absorption spectroscopy method, or the like.

  The flow control of the material gas is performed by controlling the second valve so that the deviation between the set flow rate set and the calculated flow rate of the material gas calculated based on the measured concentration and the measured carrier gas flow rate becomes small. 32 may be controlled.

  If only the concentration of the material gas in the mixed gas has only to be controlled accurately and the flow rate is not limited to a certain value but only needs to flow stably, the concrete controller 2 to the mass flow controller 3 as shown in FIG. The flow rate may be controlled without feeding back the measured concentration. In this case, the set carrier gas flow rate may be calculated based on the formula (3) from the set concentration and the set flow rate. Even if the carrier gas flow rate is set in advance and the carrier gas flows at that flow rate, if the concentration is kept constant by the concrete controller 2, as a result, the material gas or the mixed gas The flow rate is also constant. When the set carrier gas flow rate is determined in advance, the set carrier gas flow rate setting unit 333 may be omitted, and the set carrier gas flow rate may be directly input to the second valve control unit 332.

  In the above embodiment, the concentration measuring unit includes the pressure gauge for measuring the total pressure of the mixed gas and the partial pressure measuring sensor. However, the concentration measuring unit is a single unit such as an ultrasonic densitometer. May be used. Moreover, although the pressure gauge for measuring the concentration and the pressure gauge used for controlling the first valve were used in common, each may be provided separately. The measuring unit may not use the total pressure as described above.

  In the embodiment, the set temperature is changed by monitoring the opening degree of the first valve 23 by the temperature adjusting mechanism 4, but the set temperature is set by monitoring the partial pressure of the material gas. You may change suitably. Specifically, as shown in FIG. 7, the partial pressure measured by the partial pressure measurement sensor 21 is lower than the lower limit threshold partial pressure determined based on the opening limit opening of the movable range of the first valve 23. In this case, the temperature setting unit 42 may change the set temperature to a temperature higher than the set temperature set at that time. In such a configuration, it is not necessary to monitor the opening degree of the first valve 23, and by using the value of the partial pressure measurement sensor 21 as it is, a problem that the first valve 23 stops can be prevented.

  In addition to monitoring the partial pressure of the material gas and changing the set temperature, for example, the total pressure of the mixed gas output from the pressure gauge is monitored, and the lower threshold value determined based on the opening limit opening When the total pressure falls below the total pressure, the set temperature may be changed.

  In the embodiment, the partial pressure of the material gas is increased by changing the temperature in the tank 13 so that the partial pressure of the material gas can be controlled within the movable range of the first valve 23. You may take a method other than changing. That is, as shown in FIG. 8, the auxiliary valve 5 provided upstream or downstream of the first valve 23 and the auxiliary valve control unit 6 for controlling the opening degree of the auxiliary valve 5 are provided, and the first valve When the opening of 5 exceeds the open side threshold opening determined based on the opening limit opening of the movable range, the auxiliary valve controller 6 sets the opening of the auxiliary valve 5 at that time. The material gas concentration control system 100 may be characterized in that the opening degree is changed to the opening degree on the open side rather than the opening degree that is set.

  More specifically, when the auxiliary valve 5 provided in the chamber C such as the reaction chamber connected to the outlet pipe 12 is used and the opening degree of the first valve 23 becomes the open side threshold opening degree, The auxiliary valve 5 may be opened so that the total pressure can be further reduced. Further, instead of monitoring the opening degree of the first valve 23, the partial pressure of the material gas may be monitored. In addition, the auxiliary valve 5 may be provided in the outlet pipe 12.

  In the said embodiment, although it was set as the structure intended to prevent the 1st valve | bulb becoming opening limit opening degree, it may prevent conversely becoming closing | closing limit opening degree. Specifically, when the opening degree of the first valve falls below the closing side threshold opening degree determined based on the closing limit opening degree of the movable range, the temperature setting unit is set at that time. What is necessary is just to be comprised so that preset temperature may be changed into temperature lower than the preset temperature which is. In such a case, for example, the partial pressure of the material gas becomes excessively high, and the inconvenience that the total pressure corresponding to the partial pressure cannot be achieved in the movable range of the first valve can be prevented. .

  The opening threshold opening may be determined based on the opening limit opening. For example, an opening degree between the opening limit opening degree and the median value of the movable range may be used. In addition, a program that exhibits the functions as the temperature setting unit and the concentration control unit may be installed in an existing material gas concentration control system or the like. In the above embodiment, the opening itself is monitored and a threshold is set for the opening. For example, an upper limit threshold change rate is set for the measured change rate of the opening itself. If the upper limit threshold change rate is exceeded, the set temperature may be increased. In this case, the rate of change may be one in which only the absolute value is viewed, or the sign may be taken into consideration. Further, the opening-side threshold opening is not changed according to the rate of change of the opening of the first valve, and may be always fixed. For example, the opening side threshold opening is fixed at an opening of a predetermined ratio of the opening limit opening such that 95% of the opening limit opening is the opening side threshold opening. It does not matter.

  In the embodiment, when the concentration of the material gas is kept constant, the generation amount of the material gas is reduced, and the opening of the first valve is prevented from becoming the open limit opening and the concentration control is impossible. However, for example, when the flow rate control is performed so that the flow rate of the material gas is constant, the opening degree of the valve for flow rate control becomes the open limit opening degree, and the flow rate cannot be kept constant. May be prevented. Specifically, a tank for storing the material, an introduction pipe for introducing a carrier gas for vaporizing the stored material into the tank, and a mixed gas of the material gas evaporated from the material and the carrier gas from the tank. A material vaporization system including a lead-out pipe that leads out, a second valve provided on the lead-in pipe, a material gas flow rate measurement unit that measures the flow rate of the material gas, and the material gas flow rate A material gas flow rate control unit that controls the opening of the first valve so that the measured flow rate of the material gas measured by the measurement unit becomes a predetermined set flow rate, and the temperature in the tank is set as a set temperature. An opening in which the opening degree of the second valve is determined based on an opening limit opening degree of the movable range. Side threshold If it exceeds the opening degree is, the temperature setting unit may be a material gas flow control system and changes the set temperature to a temperature higher than the set temperature that is set at that time. If this is the case, it is possible to ensure a rough flow rate of the material gas by raising the temperature of the tank, preventing the opening of the second valve from reaching the opening limit opening, and the second. The flow rate of the material gas can always be kept constant by operating the valve on the median side so that fine flow rate control can be performed. The material gas flow rate measurement unit may be, for example, any one that includes a carrier gas flow rate measurement unit and the concentration measurement unit and measures the flow rate of the material gas based on the equation (3).

  In the embodiment, the material is a solid material, but may be a liquid material.

  In addition, various modifications and combinations of embodiments may be performed without departing from the spirit of the present invention.

L ... Material 1 ... Material vaporization system (Bubbling system)
DESCRIPTION OF SYMBOLS 11 ... Introducing pipe 12 ... Outlet pipe 13 ... Tank 23 ... 1st valve CS ... Concentration measurement part CC ... Concentration control part 41 ... Temperature controller 42 ... Temperature Setting part 5 ... Auxiliary valve

Claims (5)

A tank for containing the material, an introduction pipe for introducing a carrier gas for vaporizing the contained material into the tank, and a lead-out pipe for deriving a mixed gas of the material gas vaporized from the material and the carrier gas from the tank Used in a material vaporization system comprising:
A first valve provided on the outlet pipe;
A concentration measuring unit for measuring the concentration of the material gas in the mixed gas;
A concentration control unit for controlling the opening of the first valve so that the measured concentration of the material gas measured by the concentration measuring unit becomes a predetermined set concentration;
A temperature controller for adjusting the temperature in the tank so as to be a set temperature;
A temperature setting unit for setting a set temperature of the temperature controller,
When the opening degree of the first valve exceeds the opening side threshold opening degree determined based on the opening limit opening degree of the movable range, the temperature setting unit is set to be higher than the set temperature set at that time. A material gas concentration control system characterized by changing a set temperature to a higher temperature.   The material gas concentration control system according to claim 1, wherein the threshold value is changed according to a change rate of the opening degree of the first valve. A tank for containing the material, an introduction pipe for introducing a carrier gas for vaporizing the contained material into the tank, and a lead-out pipe for deriving a mixed gas of the material gas vaporized from the material and the carrier gas from the tank. Used in a material vaporization system comprising:
A first valve provided on the outlet pipe;
A partial pressure measuring sensor for measuring a partial pressure of the material gas; and a total pressure measuring sensor for measuring a total pressure of the mixed gas, and the material gas in the mixed gas based on the partial pressure and the total pressure. A concentration measuring unit for measuring the concentration of
A concentration control unit for controlling the opening of the first valve so that the measured concentration of the material gas measured by the concentration measuring unit becomes a predetermined set concentration;
A temperature controller for adjusting the temperature in the tank so as to be a set temperature;
A temperature setting unit for setting a set temperature in the temperature controller;
When the partial pressure measured by the partial pressure measurement sensor is lower than the lower limit threshold partial pressure determined based on the opening limit opening of the movable range of the first valve, the temperature setting unit at that time A material gas concentration control system characterized in that the set temperature is changed to a temperature higher than the set set temperature. A tank for containing the material, an introduction pipe for introducing a carrier gas for vaporizing the contained material into the tank, and a lead-out pipe for deriving a mixed gas of the material gas vaporized from the material and the carrier gas from the tank Used in a material vaporization system comprising:
A second valve provided on the introduction pipe;
A material gas flow rate measuring unit for measuring a flow rate of the material gas;
A material gas flow rate control unit that controls the opening of the first valve so that the measured flow rate of the material gas measured by the material gas flow rate measurement unit becomes a predetermined set flow rate;
A temperature controller for adjusting the temperature in the tank so as to be a set temperature;
A temperature setting unit for setting a set temperature of the temperature controller,
When the opening degree of the second valve exceeds the opening side threshold opening degree determined based on the opening limit opening degree of the movable range, the temperature setting unit is set to be higher than the set temperature set at that time. A material gas flow rate control system characterized by changing a set temperature to a higher temperature. A tank for containing the material, an introduction pipe for introducing a carrier gas for vaporizing the contained material into the tank, and a lead-out pipe for deriving a mixed gas of the material gas vaporized from the material and the carrier gas from the tank Used for a material vaporization system comprising
A first valve provided on the lead-out pipe, a concentration measuring unit that measures the concentration of the material gas in the mixed gas, and a measurement concentration of the material gas measured by the concentration measuring unit are set in advance. Used in a material gas concentration control system including a concentration control unit that controls the opening degree of the first valve so as to achieve a concentration, and a temperature controller that adjusts the temperature in the tank to a set temperature. A program,
A temperature setting unit for setting a set temperature of the temperature controller,
When the opening degree of the first valve exceeds the opening side threshold opening degree determined based on the opening limit opening degree of the movable range, the temperature setting unit is set to be higher than the set temperature set at that time. A material gas concentration control system program characterized by changing a set temperature to a high temperature.